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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Writing and Generating Documentation</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><meta name="keywords" content="ISO C++, documentation, style, docbook, doxygen" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="appendix_porting.html" title="Appendix B.  Porting and Maintenance" /><link rel="prev" href="appendix_porting.html" title="Appendix B.  Porting and Maintenance" /><link rel="next" href="internals.html" title="Porting to New Hardware or Operating Systems" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Writing and Generating Documentation</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="appendix_porting.html">Prev</a> </td><th width="60%" align="center">Appendix B. 
  Porting and Maintenance
  
</th><td width="20%" align="right"> <a accesskey="n" href="internals.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="appendix.porting.doc"></a>Writing and Generating Documentation</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="doc.intro"></a>Introduction</h3></div></div></div><p>
      Documentation for the GNU C++ Library is created from three
      independent sources: a manual, a FAQ, and an API reference.
    </p><p>
      The sub-directory <code class="filename">doc</code>
      within the main source directory contains
      <code class="filename">Makefile.am</code> and
      <code class="filename">Makefile.in</code>, which provide rules for
      generating documentation, described in excruciating detail
      below. The <code class="filename">doc</code>
      sub-directory also contains three directories: <code class="filename">doxygen</code>, which contains scripts and
      fragments for <span class="command"><strong>doxygen</strong></span>, <code class="filename">html</code>, which contains an html
      version of the manual, and <code class="filename">xml</code>, which contains an xml version
      of the manual.
    </p><p>
      Diverging from established documentation conventions in the rest
      of the GCC project, libstdc++ does not use Texinfo as a markup
      language. Instead, Docbook is used to create the manual and the
      FAQ, and Doxygen is used to construct the API
      reference. Although divergent, this conforms to the GNU Project
      recommendations as long as the output is of sufficient quality,
      as per
      <a class="link" href="http://www.gnu.org/prep/standards/standards.html#Documentation" target="_top">
      GNU Manuals</a>.
    </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="doc.generation"></a>Generating Documentation</h3></div></div></div><p>
      Certain Makefile rules are required by the GNU Coding
      Standards. These standard rules generate HTML, PDF, XML, or man
      files. For each of the generative rules, there is an additional
      install rule that is used to install any generated documentation
      files into the prescribed installation directory. Files are
      installed into <code class="filename">share/doc</code>
      or <code class="filename">share/man</code> directories.
    </p><p>
      The standard Makefile rules are conditionally supported, based
      on the results of examining the host environment for
      prerequisites at configuration time. If requirements are not
      found, the rule is aliased to a dummy rule that does nothing,
      and produces no documentation. If the requirements are found,
      the rule forwards to a private rule that produces the requested
      documentation.
    </p><p>
      For more details on what prerequisites were found and where,
      please consult the file <code class="filename">config.log</code> in the
      libstdc++ build directory. Compare this log to what is expected
      for the relevant Makefile conditionals:
      <code class="literal">BUILD_INFO</code>, <code class="literal">BUILD_XML</code>,
      <code class="literal">BUILD_HTML</code>, <code class="literal">BUILD_MAN</code>,
      <code class="literal">BUILD_PDF</code>, and <code class="literal">BUILD_EPUB</code>.
    </p><p>
      Supported Makefile rules:
    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">
	  <span class="emphasis"><em>make html</em></span>
	, </span><span class="term">
	  <span class="emphasis"><em>make install-html</em></span>
	</span></dt><dd><p>
	    Generates multi-page HTML documentation, and installs it
	    in the following directories:
	  </p><p>
	    <code class="filename">doc/libstdc++/libstdc++-api.html</code>
	  </p><p>
	    <code class="filename">doc/libstdc++/libstdc++-manual.html</code>
	  </p></dd><dt><span class="term">
	  <span class="emphasis"><em>make pdf</em></span>
	, </span><span class="term">
	  <span class="emphasis"><em>make install-pdf</em></span>
	</span></dt><dd><p>
	    Generates indexed PDF documentation, and installs it as
	    the following files:
	  </p><p>
	    <code class="filename">doc/libstdc++/libstdc++-api.pdf</code>
	  </p><p>
	    <code class="filename">doc/libstdc++/libstdc++-manual.pdf</code>
	  </p></dd><dt><span class="term">
	  <span class="emphasis"><em>make man</em></span>
	, </span><span class="term">
	  <span class="emphasis"><em>make install-man</em></span>
	</span></dt><dd><p>
	    Generates man pages, and installs it in the following directory:
	  </p><p>
	    <code class="filename">man/man3/</code>
	  </p><p>
	    The generated man pages are namespace-qualified, so to look at
	    the man page for <code class="classname">vector</code>, one would use
	    <span class="command"><strong>man std::vector</strong></span>.
	  </p></dd><dt><span class="term">
	  <span class="emphasis"><em>make epub</em></span>
	, </span><span class="term">
	  <span class="emphasis"><em>make install-epub</em></span>
	</span></dt><dd><p>
	    Generates documentation in the ebook/portable electronic
	    reader format called Epub, and installs it as the
	    following file.
	  </p><p>
	    <code class="filename">doc/libstdc++/libstdc++-manual.epub</code>
	  </p></dd><dt><span class="term">
	  <span class="emphasis"><em>make xml</em></span>
	, </span><span class="term">
	  <span class="emphasis"><em>make install-xml</em></span>
	</span></dt><dd><p>
	    Generates single-file XML documentation, and installs it
	    as the following files:
	  </p><p>
	    <code class="filename">doc/libstdc++/libstdc++-api-single.xml</code>
	  </p><p>
	    <code class="filename">doc/libstdc++/libstdc++-manual-single.xml</code>
	  </p></dd></dl></div><p>
      Makefile rules for several other formats are explicitly not
      supported, and are always aliased to dummy rules. These
      unsupported formats are: <span class="emphasis"><em>info</em></span>,
      <span class="emphasis"><em>ps</em></span>, and <span class="emphasis"><em>dvi</em></span>.
    </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="doc.doxygen"></a>Doxygen</h3></div></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="doxygen.prereq"></a>Prerequisites</h4></div></div></div><div class="table"><a id="table.doxygen_prereq"></a><p class="title"><strong>Table B.1. Doxygen Prerequisites</strong></p><div class="table-contents"><table class="table" summary="Doxygen Prerequisites" border="1"><colgroup><col align="center" class="c1" /><col align="center" class="c2" /><col align="center" class="c3" /></colgroup><thead><tr><th align="center">Tool</th><th align="center">Version</th><th align="center">Required By</th></tr></thead><tbody><tr><td align="center">coreutils</td><td align="center">8.5</td><td align="center">all</td></tr><tr><td align="center">bash</td><td align="center">4.1</td><td align="center">all</td></tr><tr><td align="center">doxygen</td><td align="center">1.7.6.1</td><td align="center">all</td></tr><tr><td align="center">graphviz</td><td align="center">2.26</td><td align="center">graphical hierarchies</td></tr><tr><td align="center">pdflatex</td><td align="center">2007-59</td><td align="center">pdf output</td></tr></tbody></table></div></div><br class="table-break" /><p>
	Prerequisite tools are Bash 2.0 or later,
	<a class="link" href="https://www.doxygen.nl" target="_top">Doxygen</a>, and
	the <a class="link" href="http://www.gnu.org/software/coreutils/" target="_top">GNU
	coreutils</a>. (GNU versions of find, xargs, and possibly
	sed and grep are used, just because the GNU versions make
	things very easy.)
      </p><p>
	To generate the pretty pictures and hierarchy
	graphs, the
	<a class="link" href="https://www.graphviz.org" target="_top">Graphviz</a> package
	will need to be installed. For PDF
	output, <a class="link" href="https://tug.org/applications/pdftex/" target="_top">
	pdflatex</a> is required as well as a number of TeX packages
	such as <span class="package">texlive-xtab</span> and
	<span class="package">texlive-tocloft</span>.
      </p><p>
	Be warned the PDF file generated via doxygen is extremely
	large. At last count, the PDF file is over three thousand
	pages. Generating this document taxes the underlying TeX
	formatting system, and will require the expansion of TeX's memory
	capacity. Specifically, the <code class="literal">pool_size</code>
	variable in the configuration file <code class="filename">texmf.cnf</code> may
	need to be increased by a minimum factor of two. Alternatively, using
	<strong class="userinput"><code>LATEX_CMD=lualatex</code></strong> might allow the docs to be
	build without running out of memory.
      </p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="doxygen.rules"></a>Generating the Doxygen Files</h4></div></div></div><p>
	The following Makefile rules run Doxygen to generate HTML
	docs, XML docs, XML docs as a single file, PDF docs, and the
	man pages. These rules are not conditional! If the required
	tools are not found, or are the wrong versions, the rule may
	end in an error.
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-html-doxygen</code></strong></pre><p>
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-xml-doxygen</code></strong></pre><p>
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-xml-single-doxygen</code></strong></pre><p>
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-pdf-doxygen</code></strong></pre><p>
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-man-doxygen</code></strong></pre><p>
      </p><p>
	Generated files are output into separate sub directories of
	<code class="filename">doc/doxygen/</code> in the
	build directory, based on the output format. For instance, the
	HTML docs will be in <code class="filename">doc/doxygen/html</code>.
      </p><p>
	Careful observers will see that the Makefile rules simply call
	a script from the source tree, <code class="filename">run_doxygen</code>, which
	does the actual work of running Doxygen and then (most
	importantly) massaging the output files. If for some reason
	you prefer to not go through the Makefile, you can call this
	script directly. (Start by passing <code class="literal">--help</code>.)
      </p><p>
	If you wish to tweak the Doxygen settings, do so by editing
	<code class="filename">doc/doxygen/user.cfg.in</code>. Notes to fellow
	library hackers are written in triple-# comments.
      </p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="doxygen.debug"></a>Debugging Generation</h4></div></div></div><p>
	  Sometimes, mis-configuration of the pre-requisite tools can
	  lead to errors when attempting to build the
	  documentation. Here are some of the obvious errors, and ways
	  to fix some common issues that may appear quite cryptic.
	</p><p>
	  First, if using a rule like <code class="code">make pdf</code>, try to
	  narrow down the scope of the error to either docbook
	  (<code class="code">make doc-pdf-docbook</code>) or doxygen (<code class="code">make
	  doc-pdf-doxygen</code>).
	</p><p>
	  Working on the doxygen path only, closely examine the
	  contents of the following build directory: <code class="filename">build/target/libstdc++-v3/doc/doxygen/latex</code>.
	  Pay attention to three files enclosed within, annotated as follows.
	</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
   <span class="emphasis"><em>refman.tex</em></span>
  </p><p>
    The actual latex file, or partial latex file. This is generated
    via <span class="command"><strong>doxygen</strong></span>, and is the LaTeX version of the
    Doxygen XML file <code class="filename">libstdc++-api.xml</code>. Go to a specific
    line, and look at the generated LaTeX, and try to deduce what
    markup in <code class="filename">libstdc++-api.xml</code> is causing it.
  </p></li><li class="listitem"><p>
   <span class="emphasis"><em>refman.log</em></span>
  </p><p>
    A log created by <span class="command"><strong>latex</strong></span> as it processes the
    <code class="filename">refman.tex</code> file. If generating the PDF fails
    look at the end of this file for errors such as:
    </p><pre class="screen">
    ! LaTeX Error: File `xtab.sty' not found.
    </pre><p>
    This indicates a required TeX package is missing. For the example
    above the <span class="package">texlive-xtab</span> package needs to be
    installed.
  </p></li><li class="listitem"><p>
   <span class="emphasis"><em>refman.out</em></span>
  </p><p>
    A log of the compilation of the converted LaTeX form to PDF. This
    is a linear list, from the beginning of the
    <code class="filename">refman.tex</code> file: the last entry of this file
    should be the end of the LaTeX file. If it is truncated, then you
    know that the last entry is the last part of the generated LaTeX
    source file that is valid. Often this file contains an error with
    a specific line number of <code class="filename">refman.tex</code> that is
    incorrect, or will have clues at the end of the file with the dump
    of the memory usage of LaTeX.
  </p></li></ul></div><p>
	  If the error at hand is not obvious after examination, a
	  fall-back strategy is to start commenting out the doxygen
	  input sources, which can be found in
	  <code class="filename">doc/doxygen/user.cfg.in</code>, look for the
	  <code class="literal">INPUT</code> tag. Start by commenting out whole
	  directories of header files, until the offending header is
	  identified. Then, read the latex log files to try and find
	  surround text, and look for that in the offending header.
	</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="doxygen.markup"></a>Markup</h4></div></div></div><p>
	In general, libstdc++ files should be formatted according to
	the rules found in the
	<a class="link" href="source_code_style.html" title="Coding Style">Coding Standard</a>. Before
	any doxygen-specific formatting tweaks are made, please try to
	make sure that the initial formatting is sound.
      </p><p>
	Adding Doxygen markup to a file (informally called
	<span class="quote">“<span class="quote">doxygenating</span>”</span>) is very simple. See the
	<a class="link" href="https://www.doxygen.nl/download.html#latestman" target="_top">Doxygen
         manual</a> for details.
	We try to use a very-recent version of Doxygen.
      </p><p>
	For classes, use
	<code class="classname">deque</code>/<code class="classname">vector</code>/<code class="classname">list</code>
	and <code class="classname">std::pair</code> as examples.  For
	functions, see their member functions, and the free functions
	in <code class="filename">stl_algobase.h</code>. Member
	functions of other container-like types should read similarly to
	these member functions.
      </p><p>
	Some commentary to accompany
	the first list in the <a class="link" href="https://www.doxygen.nl/manual/docblocks.html" target="_top">Special
	Documentation Blocks</a> section of the Doxygen manual:
      </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>For longer comments, use the Javadoc style...</p></li><li class="listitem"><p>
	    ...not the Qt style. The intermediate *'s are preferred.
	  </p></li><li class="listitem"><p>
	    Use the triple-slash style only for one-line comments (the
	    <span class="quote">“<span class="quote">brief</span>”</span> mode).
	  </p></li><li class="listitem"><p>
	    This is disgusting. Don't do this.
	  </p></li></ol></div><p>
	Some specific guidelines:
      </p><p>
	Use the @-style of commands, not the !-style. Please be
	careful about whitespace in your markup comments. Most of the
	time it doesn't matter; doxygen absorbs most whitespace, and
	both HTML and *roff are agnostic about whitespace. However,
	in &lt;pre&gt; blocks and @code/@endcode sections, spacing can
	have <span class="quote">“<span class="quote">interesting</span>”</span> effects.
      </p><p>
	Use either kind of grouping, as
	appropriate. <code class="filename">doxygroups.cc</code> exists for this
	purpose. See <code class="filename">stl_iterator.h</code>
	for a good example of the <span class="quote">“<span class="quote">other</span>”</span> kind of grouping.
      </p><p>
	Markdown can be used for formatting text. Doxygen is configured to
	support this, and it is a good compromise between readable comments
	in the C++ source and nice formatting in the generated HTML.
	Please format the names of function parameters in either code font
	or italics. Use underscores or @e for emphasis when necessary.
	Use backticks or @c to refer to other standard names.
	(Examples of all these abound in the present code.)
      </p><p>
	Complicated math functions should use the multi-line format.
	An example from <code class="filename">random.h</code>:
      </p><p>
</p><div class="literallayout"><p><br />
/**<br />
 * @brief A model of a linear congruential random number generator.<br />
 *<br />
 * @f[<br />
 *     x_{i+1}\leftarrow(ax_{i} + c) \bmod m<br />
 * @f]<br />
 */<br />
</p></div><p>
      </p><p>
	One area of note is the markup required for
	<code class="literal">@file</code> markup in header files. Two details
	are important: for filenames that have the same name in
	multiple directories, include part of the installed path to
	disambiguate. For example:
      </p><p>
</p><div class="literallayout"><p><br />
/** @file debug/vector<br />
 *  This file is a GNU debug extension to the Standard C++ Library.<br />
 */<br />
</p></div><p>
      </p><p>
	The other relevant detail for header files is the use of a
	libstdc++-specific doxygen alias that helps distinguish
	between public header files (like <code class="filename">random</code>)
	from implementation or private header files (like
	<code class="filename">bits/c++config.h</code>.) This alias is spelled
	<code class="literal">@headername</code> and can take one or two
	arguments that detail the public header file or files that
	should be included to use the contents of the file. All header
	files that are not intended for direct inclusion must use
	<code class="literal">headername</code> in the <code class="literal">file</code>
	block. An example:
      </p><p>
</p><div class="literallayout"><p><br />
/** @file bits/basic_string.h<br />
 *  This is an internal header file, included by other library headers.<br />
 *  Do not attempt to use it directly. @headername{string}<br />
 */<br />
</p></div><p>
      </p><p>
	Be careful about using certain, special characters when
	writing Doxygen comments. Single and double quotes, and
	separators in filenames are two common trouble spots. When in
	doubt, consult the following table.
      </p><div class="table"><a id="table.doxygen_cmp"></a><p class="title"><strong>Table B.2. HTML to Doxygen Markup Comparison</strong></p><div class="table-contents"><table class="table" summary="HTML to Doxygen Markup Comparison" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /></colgroup><thead><tr><th align="left">HTML</th><th align="left">Doxygen</th><th align="left">Markdown</th></tr></thead><tbody><tr><td align="left">\</td><td align="left">\\</td><td align="left">\\</td></tr><tr><td align="left">"</td><td align="left">\"</td><td align="left">\"</td></tr><tr><td align="left">'</td><td align="left">\'</td><td align="left">\'</td></tr><tr><td align="left">&lt;i&gt;</td><td align="left">@a word</td><td align="left">_word_ or *word*</td></tr><tr><td align="left">&lt;b&gt;</td><td align="left">@b word</td><td align="left">**word** or __word__</td></tr><tr><td align="left">&lt;code&gt;</td><td align="left">@c word</td><td align="left">`word`</td></tr><tr><td align="left">&lt;em&gt;</td><td align="left">@a word</td><td align="left">_word_ or *word*</td></tr><tr><td align="left">&lt;em&gt;</td><td align="left">&lt;em&gt;two words or more&lt;/em&gt;</td><td align="left">_two words or more_</td></tr></tbody></table></div></div><br class="table-break" /></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="doc.docbook"></a>Docbook</h3></div></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="docbook.prereq"></a>Prerequisites</h4></div></div></div><div class="table"><a id="table.docbook_prereq"></a><p class="title"><strong>Table B.3. Docbook Prerequisites</strong></p><div class="table-contents"><table class="table" summary="Docbook Prerequisites" border="1"><colgroup><col align="center" class="c1" /><col align="center" class="c2" /><col align="center" class="c3" /></colgroup><thead><tr><th align="center">Tool</th><th align="center">Version</th><th align="center">Required By</th></tr></thead><tbody><tr><td align="center">docbook5-style-xsl</td><td align="center">1.76.1</td><td align="center">all</td></tr><tr><td align="center">xsltproc</td><td align="center">1.1.26</td><td align="center">all</td></tr><tr><td align="center">xmllint</td><td align="center">2.7.7</td><td align="center">validation</td></tr><tr><td align="center">dblatex</td><td align="center">0.3</td><td align="center">pdf output</td></tr><tr><td align="center">pdflatex</td><td align="center">2007-59</td><td align="center">pdf output</td></tr><tr><td align="center">docbook2X</td><td align="center">0.8.8</td><td align="center">info output</td></tr><tr><td align="center">epub3 stylesheets</td><td align="center">b3</td><td align="center">epub output</td></tr></tbody></table></div></div><br class="table-break" /><p>
	An XML editor is recommended for editing the DocBook sources. Many
	exist: some notable options
	include <span class="command"><strong>emacs</strong></span>, <span class="application">Kate</span>,
	or <span class="application">Conglomerate</span>.
      </p><p>
	Some editors support special <span class="quote">“<span class="quote">XML Validation</span>”</span>
	modes that can validate the file as it is
	produced. Recommended is the <span class="command"><strong>nXML Mode</strong></span>
	for <span class="command"><strong>emacs</strong></span>.
      </p><p>
	Besides an editor, additional DocBook files and XML tools are
	also required.
      </p><p>
	Access to the DocBook 5.0 stylesheets and schema is required. The
	stylesheets are usually packaged by vendor, in something
	like <code class="filename">docbook5-style-xsl</code>. To exactly match
	generated output, please use a version of the stylesheets
	equivalent
	to <code class="filename">docbook5-style-xsl-1.75.2-3</code>. The
	installation directory for this package corresponds to
	the <code class="literal">XSL_STYLE_DIR</code>
	in <code class="filename">doc/Makefile.am</code> and defaults
	to <code class="filename">/usr/share/sgml/docbook/xsl-ns-stylesheets</code>.
      </p><p>
	For processing XML, an XSLT processor and some style
	sheets are necessary. Defaults are <span class="command"><strong>xsltproc</strong></span>
	provided by <code class="filename">libxslt</code>.
      </p><p>
	For validating the XML document, you'll need
	something like <span class="command"><strong>xmllint</strong></span> and access to the
	relevant DocBook schema. These are provided
	by a vendor package like <code class="filename">libxml2</code> and <code class="filename">docbook5-schemas-5.0-4</code>
      </p><p>
	For PDF output, something that transforms valid Docbook XML to PDF is
	required. Possible solutions include <a class="link" href="https://dblatex.sourceforge.net" target="_top">dblatex</a>,
	<span class="command"><strong>xmlto</strong></span>, or <span class="command"><strong>prince</strong></span>. Of
	these, <span class="command"><strong>dblatex</strong></span> is the default.
	Please consult the <code class="email">&lt;<a class="email" href="mailto:libstdc++@gcc.gnu.org">libstdc++@gcc.gnu.org</a>&gt;</code> list when
	preparing printed manuals for current best practice and
	suggestions.
      </p><p>
	For Texinfo output, something that transforms valid Docbook
	XML to Texinfo is required. The default choice is <a class="link" href="https://docbook2x.sourceforge.net/" target="_top">docbook2X</a>.
      </p><p>
	For epub output, the <a class="link" href="https://sourceforge.net/projects/docbook/files/epub3/" target="_top">stylesheets</a> for EPUB3 are required. These stylesheets are still in development. To validate the created file, <a class="link" href="https://github.com/w3c/epubcheck" target="_top">epubcheck</a> is necessary.
      </p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="docbook.rules"></a>Generating the DocBook Files</h4></div></div></div><p>
	The following Makefile rules generate (in order): an HTML
	version of all the DocBook documentation, a PDF version of the
	same, and a single XML document.  These rules are not
	conditional! If the required tools are not found, or are the
	wrong versions, the rule may end in an error.
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-html-docbook</code></strong></pre><p>
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-pdf-docbook</code></strong></pre><p>
      </p><p>
      </p><pre class="screen"><strong class="userinput"><code>make doc-xml-single-docbook</code></strong></pre><p>
      </p><p>
	Generated files are output into separate sub-directores of
	<code class="filename">doc/docbook/</code> in the
	build directory, based on the output format. For instance, the
	HTML docs will be in <code class="filename">doc/docbook/html</code>.
      </p><p>
	The <strong class="userinput"><code>doc-html-docbook-regenerate</code></strong> target will
	generate the HTML files and copy them back to the libstdc++ source tree.
	This can be used to update the HTML files that are checked in to
	version control.
      </p><p>
	If the Docbook stylesheets are installed in a custom location,
	one can use the variable <code class="literal">XSL_STYLE_DIR</code> to
	override the Makefile defaults. For example:
      </p><pre class="screen">
	<strong class="userinput"><code>
make <code class="literal">XSL_STYLE_DIR="/usr/share/xml/docbook/stylesheet/nwalsh"</code> doc-html-docbook
	</code></strong>
      </pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="docbook.debug"></a>Debugging Generation</h4></div></div></div><p>
	  Sometimes, mis-configuration of the pre-requisite tools can
	  lead to errors when attempting to build the
	  documentation. Here are some of the obvious errors, and ways
	  to fix some common issues that may appear quite cryptic.
	</p><p>
	  First, if using a rule like <code class="code">make pdf</code>, try to
	  narrow down the scope of the error to either docbook
	  (<code class="code">make doc-pdf-docbook</code>) or doxygen (<code class="code">make
	  doc-pdf-doxygen</code>).
	</p><p>
	  Working on the docbook path only, closely examine the
	  contents of the following build directory:
	  <code class="filename">build/target/libstdc++-v3/doc/docbook/latex</code>.
	  Pay attention to three files enclosed within, annotated as follows.
	</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
   <span class="emphasis"><em>spine.tex</em></span>
  </p><p>
    The actual latex file, or partial latex file. This is generated
    via <span class="command"><strong>dblatex</strong></span>, and is the LaTeX version of the
    DocBook XML file <code class="filename">spine.xml</code>. Go to a specific
    line, and look at the generated LaTeX, and try to deduce what
    markup in <code class="filename">spine.xml</code> is causing it.
  </p></li><li class="listitem"><p>
   <span class="emphasis"><em>spine.out</em></span>
  </p><p>
    A log of the conversion from the XML form to the LaTeX form. This
    is a linear list, from the beginning of the
    <code class="filename">spine.xml</code> file: the last entry of this file
    should be the end of the DocBook file. If it is truncated, then
    you know that the last entry is the last part of the XML source
    file that is valid. The error is after this point.
  </p></li><li class="listitem"><p>
   <span class="emphasis"><em>spine.log</em></span>
  </p><p>
    A log of the compilation of the converted LaTeX form to pdf. This
    is a linear list, from the beginning of the
    <code class="filename">spine.tex</code> file: the last entry of this file
    should be the end of the LaTeX file. If it is truncated, then you
    know that the last entry is the last part of the generated LaTeX
    source file that is valid. Often this file contains an error with
    a specific line number of <code class="filename">spine.tex</code> that is
    incorrect.
  </p></li></ul></div><p>
	  If the error at hand is not obvious after examination, or if one
	  encounters the inscruitable <span class="quote">“<span class="quote">Incomplete
	  \ifmmode</span>”</span> error, a fall-back strategy is to start
	  commenting out parts of the XML document (regardless of what
	  this does to over-all document validity). Start by
	  commenting out each of the largest parts of the
	  <code class="filename">spine.xml</code> file, section by section,
	  until the offending section is identified.
	</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="docbook.validation"></a>Editing and Validation</h4></div></div></div><p>
	After editing the xml sources, please make sure that the XML
	documentation and markup is still valid. This can be
	done easily, with the following validation rule:
      </p><pre class="screen">
	<strong class="userinput"><code>make doc-xml-validate-docbook</code></strong>
      </pre><p>
	This is equivalent to doing:
      </p><pre class="screen">
	<strong class="userinput"><code>
	  xmllint --noout --valid <code class="filename">xml/index.xml</code>
	</code></strong>
      </pre><p>
	Please note that individual sections and chapters of the
	manual can be validated by substituting the file desired for
	<code class="filename">xml/index.xml</code> in the command
	above. Reducing scope in this manner can be helpful when
	validation on the entire manual fails.
      </p><p>
	All Docbook xml sources should always validate. No excuses!
      </p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="docbook.examples"></a>File Organization and Basics</h4></div></div></div><div class="literallayout"><p><br />
      <span class="emphasis"><em>Which files are important</em></span><br />
<br />
      All Docbook files are in the directory<br />
      libstdc++-v3/doc/xml<br />
<br />
      Inside this directory, the files of importance:<br />
      spine.xml	 	- index to documentation set<br />
      manual/spine.xml  - index to manual<br />
      manual/*.xml  	- individual chapters and sections of the manual<br />
      faq.xml  		- index to FAQ<br />
      api.xml  		- index to source level / API<br />
<br />
      All *.txml files are template xml files, i.e., otherwise empty files with<br />
      the correct structure, suitable for filling in with new information.<br />
<br />
      <span class="emphasis"><em>Canonical Writing Style</em></span><br />
<br />
      class template<br />
      function template<br />
      member function template<br />
      (via C++ Templates, Vandevoorde)<br />
<br />
      class in namespace std: allocator, not std::allocator<br />
<br />
      header file: iostream, not &lt;iostream&gt;<br />
<br />
<br />
      <span class="emphasis"><em>General structure</em></span><br />
<br />
      &lt;set&gt;<br />
      &lt;book&gt;<br />
      &lt;/book&gt;<br />
<br />
      &lt;book&gt;<br />
      &lt;chapter&gt;<br />
      &lt;/chapter&gt;<br />
      &lt;/book&gt;<br />
<br />
      &lt;book&gt;<br />
      &lt;part&gt;<br />
      &lt;chapter&gt;<br />
      &lt;section&gt;<br />
      &lt;/section&gt;<br />
<br />
      &lt;sect1&gt;<br />
      &lt;/sect1&gt;<br />
<br />
      &lt;sect1&gt;<br />
      &lt;sect2&gt;<br />
      &lt;/sect2&gt;<br />
      &lt;/sect1&gt;<br />
      &lt;/chapter&gt;<br />
<br />
      &lt;chapter&gt;<br />
      &lt;/chapter&gt;<br />
      &lt;/part&gt;<br />
      &lt;/book&gt;<br />
<br />
      &lt;/set&gt;<br />
    </p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="docbook.markup"></a>Markup By Example</h4></div></div></div><p>
	Complete details on Docbook markup can be found in the
	<a class="link" href="https://tdg.docbook.org/tdg/5.0/ref-elements.html" target="_top">DocBook Element Reference</a>.
	An incomplete reference for HTML to Docbook conversion is
	detailed in the table below.
      </p><div class="table"><a id="table.docbook_cmp"></a><p class="title"><strong>Table B.4. HTML to Docbook XML Markup Comparison</strong></p><div class="table-contents"><table class="table" summary="HTML to Docbook XML Markup Comparison" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /></colgroup><thead><tr><th align="left">HTML</th><th align="left">Docbook</th></tr></thead><tbody><tr><td align="left">&lt;p&gt;</td><td align="left">&lt;para&gt;</td></tr><tr><td align="left">&lt;pre&gt;</td><td align="left">&lt;computeroutput&gt;, &lt;programlisting&gt;,
	&lt;literallayout&gt;</td></tr><tr><td align="left">&lt;ul&gt;</td><td align="left">&lt;itemizedlist&gt;</td></tr><tr><td align="left">&lt;ol&gt;</td><td align="left">&lt;orderedlist&gt;</td></tr><tr><td align="left">&lt;il&gt;</td><td align="left">&lt;listitem&gt;</td></tr><tr><td align="left">&lt;dl&gt;</td><td align="left">&lt;variablelist&gt;</td></tr><tr><td align="left">&lt;dt&gt;</td><td align="left">&lt;term&gt;</td></tr><tr><td align="left">&lt;dd&gt;</td><td align="left">&lt;listitem&gt;</td></tr><tr><td align="left">&lt;a href=""&gt;</td><td align="left">&lt;ulink url=""&gt;</td></tr><tr><td align="left">&lt;code&gt;</td><td align="left">&lt;literal&gt;, &lt;programlisting&gt;</td></tr><tr><td align="left">&lt;strong&gt;</td><td align="left">&lt;emphasis&gt;</td></tr><tr><td align="left">&lt;em&gt;</td><td align="left">&lt;emphasis&gt;</td></tr><tr><td align="left">"</td><td align="left">&lt;quote&gt;</td></tr></tbody></table></div></div><br class="table-break" /><p>
  And examples of detailed markup for which there are no real HTML
  equivalents are listed in the table below.
</p><div class="table"><a id="table.docbook_elem"></a><p class="title"><strong>Table B.5. Docbook XML Element Use</strong></p><div class="table-contents"><table class="table" summary="Docbook XML Element Use" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /></colgroup><thead><tr><th align="left">Element</th><th align="left">Use</th></tr></thead><tbody><tr><td align="left">&lt;structname&gt;</td><td align="left">&lt;structname&gt;char_traits&lt;/structname&gt;</td></tr><tr><td align="left">&lt;classname&gt;</td><td align="left">&lt;classname&gt;string&lt;/classname&gt;</td></tr><tr><td align="left">&lt;function&gt;</td><td align="left">
	<p>&lt;function&gt;clear()&lt;/function&gt;</p>
	<p>&lt;function&gt;fs.clear()&lt;/function&gt;</p>
      </td></tr><tr><td align="left">&lt;type&gt;</td><td align="left">&lt;type&gt;long long&lt;/type&gt;</td></tr><tr><td align="left">&lt;varname&gt;</td><td align="left">&lt;varname&gt;fs&lt;/varname&gt;</td></tr><tr><td align="left">&lt;literal&gt;</td><td align="left">
	<p>&lt;literal&gt;-Weffc++&lt;/literal&gt;</p>
	<p>&lt;literal&gt;rel_ops&lt;/literal&gt;</p>
      </td></tr><tr><td align="left">&lt;constant&gt;</td><td align="left">
	<p>&lt;constant&gt;_GNU_SOURCE&lt;/constant&gt;</p>
	<p>&lt;constant&gt;3.0&lt;/constant&gt;</p>
      </td></tr><tr><td align="left">&lt;command&gt;</td><td align="left">&lt;command&gt;g++&lt;/command&gt;</td></tr><tr><td align="left">&lt;errortext&gt;</td><td align="left">&lt;errortext&gt;In instantiation of&lt;/errortext&gt;</td></tr><tr><td align="left">&lt;filename&gt;</td><td align="left">
	<p>&lt;filename class="headerfile"&gt;ctype.h&lt;/filename&gt;</p>
	<p>&lt;filename class="directory"&gt;/home/gcc/build&lt;/filename&gt;</p>
	<p>&lt;filename class="libraryfile"&gt;libstdc++.so&lt;/filename&gt;</p>
      </td></tr></tbody></table></div></div><br class="table-break" /></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="appendix_porting.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="appendix_porting.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="internals.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Appendix B. 
  Porting and Maintenance
  
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